Internal combustion engines have become widely used for driving the blades of mowers and other lawn and garden implements. The pressure of the exhaust gases as they are emitted from the exhaust port of the engine produces a loud report, so it has become customary to equip such engines with an exhaust muffler which will help absorb the acoustical emissions during operation. The acoustical suppression has been further enhanced in some embodiments by placing the exhaust muffler below the deck of the lawn mower above the rotating blade. The problem with this embodiment is that rocks or other debris thrown up by the blade can break off the muffler from its mounting on the engine. Conventionally, exhaust mufflers are bolted onto the engine by means of one or more more threaded bolts which pass through the body of the muffler and threadably engage the external wall of the engine adjacent to the exhaust port. When the muffler is broken off, it is the mounting bolts which usually are broken off from the engine with a portion the the threaded end of the bolt remaining fastened in the engine wall. In order to repair the muffler mounting, the engine must be removed from the deck of the mower and the remaining portion of the broken bolts laboriously worked out from the engine wall. This is a time consuming procedure at best and can sometimes result in further damage to the engine wall.